Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

SURFACE-ENHANCED CANTILEVER SENSORS WITH NANO-POROUS FILMS

Developing surface-enhanced microcantilevers with improved sensitivities is of longstanding interest. In this paper, the design of surface-enhanced cantilever sensors using nano- （micro-） porous films as surface layers is proposed. The static deformation and resonance frequencies of these surface-enhanced sensors with the simultaneous effects of the eigenstrain, the surface stress and the adsorption mass are analyzed. It is shown that the sensitivities of these novel cantilever sensors for the static deformation and resonance frequencies can be tuned by the porosity, the size of the pores and the structure of the porous films. For the three kinds of cantilever consisting of solid films, films with aligned cylindrical micro-scale pores, and those with nano-scale pores, the nano-porous one has the highest static and dynamic sensitivities, whereas the solid one has the lowest.

Shape gradient and classical gradient of curvatures:driving forces on micro/nano curved surfaces

Recent experiments and molecule dynamics simulations have shown that adhesion droplets on conical surfaces may move spontaneously and directionally. Besides, this spontaneous and directional motion is independent of the hydrophilicity and hydrophobicity of the conical surfaces. Aimed at this important phenomenon, a gen- eral theoretical explanation is provided from the viewpoint of the geometrization of micro/nano mechanics on curved surfaces. In the extrinsic mechanics on micro/nano soft curved surfaces, we disclose that the curvatures and their extrinsic gradients form the driving forces on the curved spaces. This paper focuses on the intrinsic mechanics on micro/nano hard curved surfaces and the experiment on the spontaneous and directional motion. Based on the pair potentials of particles, the interactions between an isolated particle and a micro/nano hard curved surface are studied, and the geometric foundation for the interactions between the particle and the hard curved surface is analyzed. The following results are derived： （a） Whatever the exponents in the pair potentials may be, the potential of the particle/hard curved surface is always of the unified curvature form, i.e., the potential is always a unified function of the mean curvature and the Gaussian curvature of the curved surface. （b） On the basis of the curvature-based potential, the geometrization of the micro/nano mechanics on hard curved surfaces may be realized. （c） Similar to the extrinsic mechanics on micro/nano soft curved surfaces, in the intrinsic mechanics on micro/nano hard curved surfaces, the curvatures and their intrinsic gradi- ents form the driving forces on the curved spaces. In other words, either on soft curved surfaces or hard curved surfaces and either in the extrinsic mechanics or the intrinsic mechanics, the curvatures and their gradients are all essential factors for the driving forces on the curved spaces. （d） The direction of the driving force induced by the hard curved surface is independent of the hydrophilieity and hydrophobicity of the curved surface, explaining the experimental phenomenon of the spontaneous and directional motion.

Effect of a Hybrid Micro/Nano-integrated Titanium Surface on Behavior of Rat Osteoblasts

The objective of this study was to investigate the effect of a new combined micro/nanoscale implant surface feature on osteoblasts＇ behaviors including cell morphology, adhesion, proliferation, differentiation, and mineralization in vitro. A new micro/nano-hybrid topography surface was fabricated on commercial pure titanium（Cp Ti） by a two-step sandblasted acid-etching and subsequent alkali-and heattreatment（SA-AH）. The conventional sandblasted/acid-etching（SA） treatment and alkali and heat（AH） treatment were also carried out on the Cp Ti as controls. Surface microstructures of the Ti disc samples were assessed by scanning electron microscopy（SEM）. The neonatal rat calvaria-derived osteoblasts were seeded on these discs and the initial cell morphology was evaluated by SEM and immunofluorescence. Initial adhesion of the cells was then assayed by DAPI staining at 1, 2, and 4 h after seeding. The Cell Counting Kit-8（CCact K8） assay, gene expression of osteoblastic markers（ALP, Col 1, OCN, BSP, OSX, Cbfα1） and Alizarin Red S staining assays were monitored respectively for cell proliferations, differentiation and mineralization. The results show significant differences in osteoblast＇s behaviors on the four kinds of Ti surfaces. Compared with Cp Ti surface, the SA and AH treatment can significantly promote cell adhesion, differentiation and mineralization of osteoblasts. In particular, the combined SA and AH treatments exhibit synergistic effects in comparison with the treatment of SA and AH individually, and are more favorable for stimulating a series of osteogenous responses from cell adhesion to mineralization of osteoblasts. In summary, this study provides some new evidence that the integrated micro/nanostructure on the Cp Ti surface may promote bone osseointegration between the Ti implantbone interfaces in vitro.

Surface effects of adsorption-induced resonance analysis on micro/nanobeams via nonlocal elasticity

The governing differential equation of micro/nanbeams with atom/molecule adsorption is derived in the presence of surface effects using the nonlocal elasticity. The effects of the nonlocal parameter, the adsorption density, and the surface parameter on the resonant frequency of the micro/nanobeams are investigated. It is found that, in ad- dition to the nonlocal parameter and the surface parameter, the bending rigidity and the adsorption-induced mass exhibit different behaviors with the increase in the adsorption density depending on the adatom category and the substrate material.

Deformation Analysis of Micro/Nano Indentation and Diamond Grinding on Optical Glasses

The previous research of precision grinding optical glasses with electrolytic in process dressing （ELID） technology mainly concentrated on the action of ELID and machining parameters when grinding, which aim at generating very ＂smoothed＂ surfaces and reducing the subsurface damage. However, when grinding spectrosil 2000 and BK7 glass assisted with ELID technology, a deeply comparative study on material removal mechanism and the wheel wear behaviors have not been given yet. In this paper, the micro/nano indentation technique is initially applied for investigating the mechanical properties of optical glasses, whose results are then refereed to evaluate the machinability. In single grit diamond scratching on glasses, the scratching traces display four kinds of scratch characteristics according to different material removal modes. In normal grinding experiments, the result shows BK7 glass has a better machinability than that of spectrosil 2000, corresponding to what the micro/nano indentation vent revealed. Under the same grinding depth parameters, the smaller amplitude of acoustic emission （AE） raw signals, grinding force and grinding force ratio correspond to a better surface quality. While for these two kinds of glasses, with the increasing of grinding depth, the variation trends of the surface roughness, the force ratio, and the AE raw signals are contrary, which should be attributed to different material removal modes. Moreover, the SEM micrographs of used wheels surface indicate that diamond grains on the wheel surface after grinding BK7 glass are worn more severely than that of spectrosil 2000. The proposed research analyzes what happened in the grinding process with different material removal patterns, which can provide a basis for producing high-quality optical glasses and comprehensively evaluate the surface and subsurface integrity of optical glasses.

Preparation of Material Surface Structure Similarto Hydrophobic Structure of Lotus Leaf

Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol） （PVA） and polystyrene （PS） moulds of the mastoid microstructure on lotus leaf surface were prepared respectively by the nano/micro replication technology. And poly（dimethylsiloxane） （PDMS） replicas with the mastoid-like microstructure were prepared from these two kinds of polymer moulds. Scanning electronic microscope （SEM） was employed to investigate the morphology and microstructures on moulds and replicas. Both the static and dynamic contact angles between water droplet and PDMS replicas＇ surface were also measured. As a result, similar microstructure can be observed clearly on the surface of PDMS replicas and the static contact angle on PDMS replicas was enhanced dramatically by the existence of these microstructures.

Generalized model for laser-induced surface structure in metallic glass

The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.

Effect of Laser Texturing Parameters on Wettability of Nickel Surface

Wettability is an important characteristic of solid surfaces. Enhancing the surface wettability is very important for improving the properties of materials. Superhydrophobic materials show good prospects for development in areas such as self-cleaning, anti-fog snow, anti-icing, and corrosion resistance. It has become a hot spot to develop a superhydrophobic surface with low surface free energy and good anti-adhesion properties. In this paper, nanosecond pulsed lasers were used to texture the nickel surface, and the different texturing speeds were changed. Combined with the ultrasonic treatment of low surface energy materials, nickel surfaces with different contact angles were obtained. The experimental results show that low surface energy substances can increase the contact angle of nickel surface but the extent of increase is limited. Laser microstructure induces micro & nanostructures. Ultrasonic action can adsorb certain low surface energy substances on the surface, greatly improving the hydrophobic properties of the surface, the contact angle with water up to 152? and the roll angle is less than 2?, and with the increase of the laser texturing speed, the contact angle of the nickel surface shows a decreasing trend.

Ultrashort pulsed laser induced complex surface structures generated by tailoring the melt hydrodynamics

We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation.The pulse train used,in particular,consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning(DLIP).The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow,while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained.Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies.The underlying physical processes behind the complex patterns’generation were interpreted in terms of a multiscale model combining electron excitation with melt hydrodynamics.We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.

Localized in‑situ deposition:a new dimension to control in fabricating surface micro/nano structures via ultrafast laser ablation

Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.

超疏水表面加工技术及耐磨性能研究进展

当前制备的超疏水表面耐磨性能普遍较差,因而其在各领域的应用受到限制。研究表明微纳结构和低表面能是实现功能表面超疏水性能的关键因素,因此,首先基于超疏水表面作用机制,对超疏水表面织构进行了归纳,旨在通过优化表面织构来解决微纳结构易磨损难题;然后对超疏水表面加工技术进行了梳理总结,从成本和效率两个方面分析了降低表面能的措施,为拓展超疏水表面加工体系提供思路;进而详细总结了超疏水表面耐磨性的分析手段,并阐述了提高超疏水表面耐磨性的方法;最后,展望了耐磨性超疏水表面的未来发展前景,以期推动超疏水表面在工程中的大规模应用。

微纳结构表面防冰研究进展

首先从冰的2种形成机理-均相成核和非均相成核进行了阐述,并介绍了液体在固体表面上的润湿现象。在此基础上,根据微纳结构防冰机理,分别综述了在固体表面结冰的前、中、后不同时期的最新防冰除冰策略。结冰前,借助液滴的脱落和自除预防固体表面结冰;结冰时,可通过延长冰的冻结时间,延缓冰在固体表面上的覆盖;结冰后,降低冰在固体表面的附着力,使之更易脱离固体表面,达到防冰除冰的需求。最后,对于如何提高微纳结构表面的耐久性进行了总结,对有关这些问题的最新研究成果进行了归纳和讨论,并对今后微纳结构表面防冰除冰的研究进行了展望。

生物基超疏水涂层的制备及其在包装领域的应用

目的旨在通过全面综述近年来包装领域生物基超疏水涂层的研究进展,使相关研究者快速了解生物基超疏水涂层的构建策略和应用场景,为开发新一代生物基超疏水涂层提供借鉴。方法首先,对超疏水表面的构建策略进行概述,并从生物基材料来源的角度,系统总结生物基超疏水涂层的制备方法、性能特点以及在多功能包装领域的应用情况。其次,探讨目前生物基超疏水涂层面临的主要挑战和未来发展方向。结果生物基超疏水涂层在自清洁、防污、防腐、阻燃、除冰等多功能包装领域显示出优异的性能,为其未来的研究和发展提供了有力支撑。结论得益于生物基材料良好的可降解性和生物相容性,制备全生物基可降解的超疏水涂层将成为未来超疏水涂层重要的研究方向。

微纳级GaN基VCSEL中周期反射结构与电子阻挡层的设置作用分析

氮化镓(GaN)基微纳米结构生长技术的成熟为微纳级GaN基垂直腔面发射激光器(VCSEL)的制备提供了新的途径。本文设计了基于GaN基轴向异质结微纳米柱的微纳级VCSEL结构,采用Al_(0.8)Ga_(0.2)N/In_(0.2)Ga_(0.8)N应变补偿结构作为上下分布式布拉格反射镜(DBR),其中Al_(0.8)Ga_(0.2)N层的Al组分远高于传统结构中的电子阻挡层(EBL),能够更好地起到电子阻挡的作用。本文使用商用软件PICS3D构建了电子阻挡层处于不同位置的VCSEL数理模型,并进行数值模拟计算,探索和分析物理机理,解释了不同位置EBL对空穴注入效率的影响。结果表明,采用Al_(0.8)Ga_(0.2)N与In_(0.2)Ga_(0.8)N组成的应变补偿DBR可以更好地提高空穴注入效率,优化器件光电性能。

微纳米气泡共混凝工艺下多因素交互作用

为强化微纳米气泡共混凝工艺性能,本文以聚合氯化铝(PACl)、微纳米气泡进气量(Q_(g))以及溶液pH值为影响因素,以沉淀出水中腐殖酸(HA)去除效率和剩余Al^(3+)浓度为响应值,通过Box-Behnken设计(BBD)以及响应面法探究该工艺背景下各因素间的交互作用.实验结果表明,PACl投加量、Q_(g)以及pH值均能够显著影响该工艺对HA的去除效率.但对于沉淀出水中Al^(3+)浓度而言,PACl投加量以及Q_(g)均不会造成显著影响,pH值为该响应值的显著影响因素.与常规混凝工艺相比,混凝过程中微纳米气泡的参与能够显著降低沉淀出水中剩余Al^(3+)浓度,提高混凝过程中PACl的利用效率.对HA去除效率及剩余Al^(3+)浓度的综合评估结果表明,微纳米气泡共混凝工艺更适用于处理pH值为中性的原水.上述结论再次突出了微纳米气泡共混凝工艺的优越性,同时也为该工艺的工程应用提供了可靠的数据支撑和理论支持.

基于激光表面微纳结构的胶接性能研究进展

胶接具有独特的性能而被广泛关注,但在实际应用中往往由于界面结合强度不足而导致接头在服役过程中过早失效。激光表面处理是一种能够有效提高胶接接头表面性能的方法,通过激光表面处理会使黏接材料表面形成不同的表面微纳结构,从而改善接头的性能。首先介绍了激光表面处理原理及激光器分类,对比了不同激光器的优缺点及加工质量特性,分析了激光加工参数对接头强度的影响。其次从激光加工不同表面微纳结构入手,阐述了不同表面微纳结构的加工方式,分析了不同表面微纳结构对不同材料接头强度的影响。此外,针对不同的表面微纳结构,其结构参数有所不同,导致接头表面化学成分和润湿性能也有所不同,使得接头强度有所差异,在此基础上分析了微纳结构参数对接头强度的影响及原因。同时,胶层间的作用机制与接头强度具有密不可分的联系,研究表明,不同的表面微纳结构对胶层的作用机制具有明显的不同,归纳总结发现,经激光表面处理形成表面微纳结构后接头表面粗糙度、化学性质、润湿性能及胶层间裂纹的扩展对接头强度的提升具有一定作用。最后,对激光表面处理微纳结构的研究进行了展望。

激光电沉积复合制备定域微纳结构及其超疏水性能研究

目的实现金属超疏水表面特定微纳结构的定域制备。方法利用激光电沉积复合工艺(LECP)制备出由Cu微米锥和Ni纳米锥所组成的定域微纳结构。首先,依次使用800目和2000目砂纸机械抛光纯铜表面,皮秒激光刻蚀纯铜表面,获得周期性的微米锥结构,并电解去除熔融产物。在电沉积加工过程中引入激光辐照,进而控制Ni纳米锥结构的定域生长。分别将机械抛光、激光刻蚀、激光刻蚀后电沉积(常温、60℃)、LECP所制备的微纳结构表面进行化学改性处理,对所得样品的表面形貌、化学成分、疏水性能、自清洁、延迟结冰和耐腐蚀性能进行对比分析。结果与激光刻蚀后电沉积相比,LECP能够定域制备Ni纳米锥结构。LECP定域制备的微纳结构表面经化学改性后实现了超疏水,其接触角为163°±2°,滚动角为1°±0.5°。与未加工微纳结构的表面相比,LECP制备样品表面水滴结冰时间延长近5倍,腐蚀电流密度减小了2个数量级。结论本研究通过LECP实现了表面微纳结构的定域制备,为超疏水表面的应用提供了一种新的技术手段。

基于激光加工的医疗器械功能性表面研究现状

制备功能性表面是提升医疗器械治疗性能和安全性的重要方法之一。当前,基于激光加工的功能性表面微纳结构制造技术在优化医疗器械表面性能方面应用广泛。综述了医疗植入器械和手术器械表面激光加工功能性微纳结构在细胞功能调控、抗菌性、耐蚀性、摩擦特性、抗黏附性等方面的研究现状,剖析了当前医疗器械功能性表面激光加工的优势和局限,展望了医疗器械功能性表面激光加工技术的发展前景。